I recently saw this chart on startup risks by venture capital stage. I bring this topic up with founders often to give them an idea of what follow-on investors think about. For us, market risk is baked in from the very beginning. We make an assessment of market or demand risks as part of our diligence prior to investing. Most founders we chat with and eventually invest in know the product they want to build or the market they want to serve.
I'd add "coaching" founders, and referring them to professional coaches to all of the above!